Interfacial Co-OV-Mg active centers in valence-tailored solid solutions for mild and efficient CO2 cycloaddition

The construction of efficient interfacial active sites in metal oxides remains a major challenge for driving the CO 2 cycloaddition under mild conditions. Herein, we engineered a Co x Mg 1-x O solid solution catalyst via a controlled reduction strategy, which achieves near-atomic dispersion within the MgO lattice. The catalyst delivers 96 % yield of cyclic carbonate from epichlorohydrin at 90 °C and 0.1 MPa CO 2 , surpassing the performance of benchmark MgO and Co 3 O 4 catalysts and maintaining stability over five cycles. Structural and spectroscopic characterization (XRD, XPS, UV-Vis) combined with DFT calculations reveal that the high activity originates from synergistic Co-O V -Mg interfacial sites, where Lewis acidic Co 2 + activates epoxides and adjacent oxygen vacancies facilitate CO 2 adsorption. This synergistic effect lowers the energy barrier for the rate-determining ring-opening step to 0.37 eV. This work demonstrates the rational design of oxide solid solutions to create cooperative interfacial sites for efficient CO 2 conversion under mild conditions.